Thyroid Nodules

What Are Thyroid Nodules? What Causes Thyroid Nodules?

Thyroid nodules are lumps which commonly arise within an otherwise normal thyroid gland. They indicate a thyroid neoplasm, but only a small percentage of these are thyroid cancers. Often these abnormal growths of thyroid tissue are located at the edge of the thyroid gland so they can be felt as a lump in the throat. When they are large or when they occur in very thin individuals, they can even sometimes be seen as a lump in the front of the neck.

A thyroid nodule can occur in any part of the gland. Some nodules can be felt quite easily, while others can be hidden deep in the thyroid tissue or located very low in the gland where they are difficult to feel.

Thyroid nodules may be single or multiple. A thyroid gland that contains multiple nodules is referred to as a multinodular goiter. If the nodule is filled with fluid or blood, it is called a thyroid cyst. If the nodule produces thyroid hormone in an uncontrolled manner without regard to the body's needs, the nodule is referred to as autonomous.

Eighty five percent of nodules are cold. Of these, up to 25% are malignant, while 5% of nodules are hot. Among these, 1% are malignant.

What are symptoms of Thyroid Nodules?

A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom while dilated pupils may be a sign.

Worrisome signs and symptoms include voice hoarseness, rapid increase in size, compressive symptoms (such as dyspnoea or dysphagia) and appearance of lymphadenopathy.

A small number of patients complain of pain at the site of the nodule that can travel to the ear or jaw. If the nodule is very large, it can compress the esophagus or trachea and cause difficulty swallowing or shortness of breath.

What causes Thyroid Nodules?

The cause of most thyroid nodules is not known. Severe iodine deficiency may lead to nodules. The body needs iodine to make thyroxine. Reaction of the thyroid including inflammation or swelling of the gland may occur in response to a viral infection or to drugs such as amiodarone or lithium. There also are certain genes that may be involved in the development of nodules in some individuals.

In rare cases, a problem with the pituitary gland may be the culprit. The pituitary gland regulates the thyroid, so damage to the pituitary may lead to hypothyroidism and telling nodules.

Diagnosing Thyroid Nodules

One approach used to determine whether the nodule is malignant is the fine needle biopsy, which some have described as the most cost-effective, sensitive and accurate test. Usually a fine needle biopsy yields sufficient thyroid cells to assess the risk of malignancy, although in some cases, the suspected nodule may need to be removed surgically for pathological examination. Rarely, a biopsy is done using a large cutting needle, so that a piece of nodule capsule can be obtained.
Blood or imaging tests may be done prior to or in lieu of a biopsy. The possibility of a nodule which secretes thyroid hormone, which is less likely to be cancer, or hypothyroidism is investigated by measuring thyroid stimulating hormone, and the thyroid hormones thyroxine and triiodothyronine. Tests for serum thyroid autoantibodies are sometimes done as these may indicate autoimmune thyroid disease which can mimic nodular disease.

Radionuclide scanning with radioactive chemicals is another imaging technique a physician may use to evaluate a thyroid nodule. The normal thyroid gland accumulates iodine from the blood and uses it to make thyroid hormones. Thus, when radioactive iodine is administered orally or intravenously to an individual, it accumulates in the thyroid and causes the gland to "light up" when imaged by a nuclear camera. The rate of accumulation gives an indication of how the thyroid gland and any nodules are functioning.

What are the treatment options for Thyroid Modules?

Treatments include destroying the gland using radioactive iodine, blocking the production of thyroid hormone with medications, or just following a patient if the hyperthyroidism is mild.

Removal surgery is also an option and is recommended when a nodule is in excess of 4cm, a complex cyst is seen on ultrasound, compressive symptoms are present or signs of malignancy including vocal cord dysfunction are apparent.